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Originally Posted by redforever
The birds did not evolve or change their beaks. The ones with large beaks died, leaving only small beaked birds remaining in the gene pool. As the article says, it is gene displacement. It is a form of evolution, but it is not as some are thinking, that all the birds slowly changed their beaks over time. It happened quite rapidly and suddenly because of the fact that the large beak birds died.
But isn't that natural selection? Isn't evolution (and correct me if I'm wrong) heavily based on the theory of natural selection? When a species average beak size is 3", and 50 years later its 2" due to natural selection, isn't that micro-evolution in action?
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Yes, as the article states, it is a form of evolution, things have changed, call it survival of the fittest or whatever, for some reason or other, change has occurred. Mutation can also cause change that is genetically passed on. There are many ways that things can change or evolve.
Where some become confused is trying to figure out how say these birds could evolve and get a new beak, WITHOUT outside stimuli. In other words, would these same birds have evolved and changed the size of their beaks without having the factor of the large beaked birds die off? Would then the large beaked birds, all on their own, without external stimuli, change their beaks to be the same size of the small beaked birds?
Right now, within the human race, the young generation has bigger thumbs than their predecessors. Is this evolution? Or is it muscle development due to all the computer activity and games being played on the computer? In other words, will the thumbs of further generations stay large, will the large thumb now be passed on genetically, or will the thumb size remain the same at birth, but once again, become larger with electronic game activity?